Draw chuck with individually adjustable clamping jaws

ABSTRACT

A chuck having bell crank driven cylindrical master jaws paired with associated workpiece clamping jaws. Each clamping jaw is securely and safely locked to its master jaw and released therefrom by a clamping plate which is disposed in a radial, Tshaped slot in the clamping jaw. The plate has legs extending rearwardly into a radial passage in the master jaw engaging therein a radially disposed camming pin which is actuable to draw the clamping jaw into locked or released position with the master jaw. The clamping jaw, in its released position, is movable radially with respect to the master jaw, for adjustment or removal by sliding movement on the clamping plate. A locking pin is provided to lock each master jaw against radial movement to machine or bore the clamping jaws. A cylindrical sleeve seals the chuck against contaminating particles.

United States Patent [1 1 Hughes 11 3,744,808 July 10, 1973 DRAW CHUCKWITH INDIVIDUALLY ADJUSTABLE CLAMPING JAWS [76] lnventor: Charles R.Hughes, 308 Vista Baya, Costa Mesa, Calif.

[22] Filed: Feb. 14, 1972 [21] Appl. No.: 225,958

Related U.S. Application Data [63] Continuation-impart of Ser. No.852,651, Aug. 25,

Sloan et a]. 279/123 X Primary ExaminerAndrew R. Juhasz AssistantExaminer--James F. Coan Attorney-John R. Shewmaker [57 ABSTRACT A chuckhaving bell crank driven cylindrical master jaws paired with associatedworkpiece clamping jaws. Each clamping jaw is securely and safely lockedto its master jaw and released therefrom by a clamping plate which isdisposed in a radial, T-shaped slot in the clamping jaw. The plate haslegs extending rearwardly into a radial passage in the master jawengaging therein a radially disposed camming pin which is actuable todraw the clamping jaw into locked or released position with the masterjaw. The clamping jaw, in its released position, is movable radiallywith respect to the master jaw, for adjustment or removal by slidingmovement on the clamping plate. A locking pin is provided to lock eachmaster jaw against radial movement to machine or bore the clamping jaws.A cylindrical sleeve seals the chuck against contaminating particles.

34 Claims, 11 Drawing Figures PATENIED JUL 1 men SHEET 2 BF 2 DRAW CHUCKWITH INDIVIDUALLY ADJUSTABLE CLAMPING JAWS CROSS-REFERENCE TO RELATEDAPPLICATION This is a continuation-in-part of Applicants copendingapplication Ser. No. 852,651, filed Aug. 25, 1969 and now abandoned.

SUMMARY OF THE INVENTION being serrated thereat to present asubstantially planar,

forward-facing surface. A clamping jaw cooperates with each master jawand the back surface of the clamping jaw has mating, complementaryserrations with interengage with those of the master jaw to firmly holdthe jaws together.

The clamping jaws are clamped against the master jaws by radiallyextending clamping plates and rearwardly extending legs thereon, theplates and legs being disposed in radial T-shaped slots in andpreferably extending for the length of the clamping jaws. The plate legsextend axially through openings in each master jaw to a radiallydisposed passage therein, in which is disposed a camming pin. Thecamming pin extends through and has camming surfaces engagingopenings inboth of the plate legs and is rotatable to effect movement of the plateand the clamping jaw thereon toward and away from the master jaw. Acompression spring bears against the clamping plate to urge it and theclamping jaw away from the master jaw.

To compensate for the slight twist developed in the camming pin duringrotation, and insure that both legs are cammed together, the pin cammingsurfaces are slightly offset around the pin circumference with respectto one another, so that the clamping plate safely and securely holds theclamping jaw in its locked position on the master jaw. As a furthersafety feature, a locking detent is provided for the cam pin to preventits accidental unlocking during operation of the chuck, the detentstopping cam rotation in an intermediate position prior to completedisengagement of the mating jaw serrations.

Each master jaw has an eccentric, generally cylindrical head thereonwhich is also serrated at its front surface and which prevents rotationof the master jaw within the radial passage. Springs are located inholes in the chuck and bear against the master jaw head to bias themaster jaw for radial movement outwardly toward work releasing position.

The chuck also carries axially reciprocable locking pins for locking themaster jaws against radial movement. These pins are engaged by crankpins rotatable from the outside of the chuck, whereby the locking pinsmay be extended into the master jaws.

Bell crank levers are located in the chuck opposite the master jaws andhave their opposite legs engaged with the master jaws and with anactuator which is located centrally of the chuck and connected to thedrawbar of the machine on whose spindle the chuck is mounted, wherebyaxial movement of the actuator cffects radial movement of the jawstoward and away from a workpiece to be clamped between the clampingjaws. A bolt secured to the actuator is located to interlock with a bellcrank lever to prevent involuntary rotation of the actuator relative tothe chuck. Locking in clamping position is effected by a cam over lockarrangement on standard drawbar mechanisms.

A cylindrical sealing sleeve is disposed axially within the chuck withopposing ends in sliding, sealed engagement with the actuator and themaster jaw, respectively, to seal the internal working parts of thechuck against foreign particles and debris, such as that produced whenutilizing the chuck in a grinding operation.

It is therefore an object of this invention to provide an improved drawchuck having paired master and clamping jaws which are provided withclamping plates to clamp the clamping jaws to the master jaws, andhaving the clamping plate within a radial slot in the clamping jaw sothat each clamping jaw in its released position is freely slidableradially with respect to the master jaw for adjustment or replacement ofthe clamping jaw.

Another object of the invention is an improved chuck in accordance withthe preceding object in which each clamping plate has integral legsextending through openings in its master jaw to a radially extendingpassage therein in which is disposed a camming pin having cam surfacescooperating with openings through both the legs for moving the platetoward and away from the master jaw.

Another object of the invention is an improved chuck according to thepreceding objects and including a manually movable pin for locking themaster jaws against movement, at which time the clamping jaws can bebored or otherwise machined in conformance with the shape of theworkpiece to be clamped between the clamping jaws.

With the clamping jaws individually adjustable on the master jaws, it isa feature of the invention that the relative locations of the clampingjaws can be changed to accommodate eccentricities in the shape of theworkpiece.

Another object of the invention is an improved chuck in which generallycylindrical jaws are received within corresponding cylindrical radialpassages in the chuck for radial movement therein without rotation.

Another object of the invention is an improved chuck sealed againstcontaminants to protect the chuck during grinding operations or thelike.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial longitudinalsectional view through the chuck of the present invention and showingone of the combined master and clamping jaws thereof;

FIG. 2 is a front elevation view of the chuck with parts of one of theclamping jaws broken away;

FIG. 3 is a partial top plan view from the plane 3-3 of FIG. 1;

FIG. 4 is a front elevational view of the chuck with the jaws removed toshow the bell crank arrangement;

FIG. 5 is a partial transverse sectional view on the line 5-5 of FIG. 1;

FIG. 6 is a perspective view, cut away in partial, lon gitudinalsection, of a modified form of chuck having a sealing sleeve, with oneclamping jaw shown cut away in part and the same jaw depicted in phantomoutline in an adjusted position;

FIG. 7 is an enlarged partial, longitudinal sectional view through thesealing sleeve showing the cooperative relation between the sealingsleeve and both the master jaw and chuck actuator;

FIG. 8 is a perspective view of the sealing sleeve;

FIG. 9 is a partial sectional view, along line 99 in FIG. 7, showing onecamming portion of the camming pm;

FIG. 10 is a partial section view similar to FIG. 9, but through thesecond camming portion of the camming pin illustrating the offsetrelation of the camming portions with respect to one another; and

FIG. 11 is a partial, transverse, sectional view, through the cammingpin head, showing the locking detent for the pin.

DETAILED DESCRIPTION The machine head to which the chuck of theinvention is mounted is represented in FIG. 1 as having a rotating lathespindle 11 and a rotating and axially moving drawbar 12. The chuck 13has an annular body portion 14 and a back cover 15 which is threaded at16 for mounting on the spindle 11, being held in place by a plug 17 ofsoft metal, such as brass, and a machine set screw 18. The cover 15 isconnected to the body portion 14 by annularly spaced bolts 19.

In the illustrated embodiment the chuck 13 has three pairs of clampingand master jaws angularly spaced at 120, as shown in FIG. 2. The pairsof jaws are identical and one pair only is shown in FIGS. 1, 3 and 5.The following description of clamping and master jaws is to applyequally to all three pairs.

Each master jaw 21 has a generally cylindrical body portion 22 disposedin a complementary passage 23 in the chuck body portion 14, the passage23 being open toward the front (the left side of FIG. 1) and the bodyportion 22 of the master jaw has a serrated front surface 24 providing asubstantially planar, forward-facing surface against which the clampingjaw rear surface 24a is itself clamped. The serrated surface 24 isprovided with serrations of the order of 0.050 in. apart, and theclamping jaw 25 has complementary serrations on its rear surface 24awhich mate and interengage with the serrations on the surface 24 tosecurely hold the jaws together and to permit their relative radialadjustment (vertically as viewed in FIG. 1) in short incrementsaccording to the distance between the serrations.

Each master jaw 21 has a generally cylindrical head 26 thereon which iseccentrically mounted with respect to the body portion 22 and isreceived within a cylindrical recess 27 within the chuck body 14, therecess forming a radial extension of passage 23, and the head 26 alsobeing segmented at its front to form part of the surface 24 of themaster jaw. As indicated in FIG. 3, the body portion 22 of each masterjaw has a radius r, the head 26 has a radius R, and the axes of the bodyand head are offset by a distance D. The master jaw 22 is, by itseccentric head, prevented from rotating in its passage 23 regardless ofthe presence of a clamping jaw Each clamping jaw 25 has a T-shaped slot28 extending longitudinally thereof (vertically in FIG. 1) and in aradial direction with respect to the chuck 13, which slot receives aclamping plate 29 having legs 31 and 32 integral therewith extendinginto openings 33a and 33b in the master jaw 21. Legs 31 and 32 haveopenings therethrough at 34 which align with an opening 35 extendingradially through the master jaw body portion 22, and a camming pin 36extends through the opening 35 and has camming portions 37 and 38thereon cooperating with the openings 34 in the legs 31 and 32,respectively, to draw the legs rearwardly (to the right of FIG. 1) andthe plate 29 therewith to force the clamping jaw 25 into clampedsupported position on the master jaw 21 with the complementary, matingserrations of the surface 24 and 24a securely interengaged. Acompression spring 30 biases the clamping jaw away from the master jaw.

Outside the radius r, the chuck body 14 is provided with pairs ofradially extending passages 41 in which are disposed springs 42 whichbear on the under surfaces 26a of the heads 26 to bias the master jawsradially outwardly into work releasing position.

The back cover 15 is provided with pairs of radially and axiallyextending lugs 43 in which are pivotally mounted bell crank levers 44,as on pins 45. The bell crank levers 44 have one leg 46 of each disposedin a pocket 47 in the back of a master jaw 21 and their other legs 48disposed in an annular pocket 49 in an actuator 51 threaded into thedrawbar 12 at 52, and after assembly, made non-rotatable with respect tothe chuck 13 by a volt 53 extending between the walls forming theannular pocket 49 in a position to interfere with a bell crank lever 44and thereby prevent involuntary rotation of the actuator relative to thechuck.

As the drawbar l2'and the actuator 51 are moved axially (horizontally asviewed in FIG. 1) of the machine, the bell crank levers 44 will berotated to effect radially inward and outward (vertical as viewed inFIG. 1) movements of the master jaws 21 and of the clamping jaws 25thereon into and out of clamping engagement with the workpiece, FIG. 2showing theclamping jaws moved radially inwardly into clampingengagement with a workpiece 54.

The clamping jaws 25 are preferably of soft steel so as to be easilybored or machined to the dimensions of the workpiece to be clampedtherebetween, and for this machining operation, means is provided for.locking each master jaw against radial movement. The specific meansillustrated is an axially reciprocable locking pin 55 having atransverse slot 56 therein in which engages a crank pin 57 eccentricallymounted on a radially extending pin 58. The pin 58 is held in positionby a spring-biased ball 59 pressed in a groove 61 to permit rotation ofthe pin 58 whereby the crank pin 57 reciprocates the locking pin 55 intoand out of a hole 62 in the body portion 22 of the master jaw 21.

The operation of the chuck of this invention will be apparent from theabove description. The chuck 13 is threaded onto the machine spindle 11at 16, while the set screw 18 is loosened and when the parts are tightlymounted, the set screw 18 is tightened. The actuator 51 is threaded intothe drawbar 12 by turning the drawbar.

Each pin 36 is individually rotated so that its camming portions 37 and38 move the legs 31 and 32 and the corresponding clamping plate 29axially outwardly to release its clamping jaw 25 from the master jaw 21.Each clamping jaw is then moved to and clamped in an adjusted positionwith respect to its master jaw, and the master jaws are locked inposition for a machining operation on the clamping jaws by rotation ofthe pins 58, whereby the crank pins 57 project the locking pins 55 intothe holes 62, thereby locking the master jaws against movement.Thereafter, the ends of the clamping jaws 25 may be bored, or otherwisemachined, to conform to the size and shape of the workpiece to beclamped.

The crank pins 58 are then turned to remove the pins 55 from the holes62 and the master jaws 21, with the clamping jaws 25 thereon, are thenfree to move radially inwardly and outwardly of the chuck as theactuator 51 is moved axially inwardly and outwardly by the drawbar 12.

Upon completion of the work for a given workpiece, the set-up operationmay again be initiated, as first described, with the soft clamping jaws25 again adjustably clamped to the master jaws by manipulation of thecamming pins 36 and then bored or machined to the new workpiece size,after which the jaws are manipulated together, into and out of clampingrelation with the workpiece, by axial movement of the drawbar 12rotating the bell crank levers 44 through the actuator 51.

FIGS. 6-11 depict an alternate form of the chuck 13 having certainmodifications to seal the chuck parts from contaminating particles andto securely clamp the master and clamping jaws together with the cam pin36 held against accidental unlocking. In FIGS. 6-11 the same numeralsare used to designate the same elements as those shown and described inconnection with FIGS. l-5.

In certain operations, such as grinding for example, small particles anddebris readily collect in the central, axially extending passage of thechuck body 14. When this occurs, the particles are thrown radiallyoutward by centrifugal force into the radially extending, master jawpassages 23, the cam pin openings 35, and the clamping plate legopenings 33a and 33b. As a result, the particles collect in the workingparts of the chuck and eventually interfere with or prevent normaloperation.

In order to seal these passages and prevent the particles frompenetrating into the chuck, a generally cylindrical sealing sleeve 70,illustrated in FIG. 8, is disposed axially within the chuck body 14 inthe manner depicted in FIGS. 6 and 7. An outwardly extending, annularshoulder 71 is formed around the sleeve intermediate its front and rearends, and a spring-steel snap ring 72 anchored in the chuck body bearsagainst the shoulder to hold the sleeve in place restrained againstmovement.

The front end of the sleeve 70 includes an annular flange 73 with asealing ring groove 74 formed in its front surface 75 for receiving aconventional O-ring 76. As shown in FIGS. 6 and 7, the front sleevesurface 75 is disposed in working relationship with a rear facingsurface 77 of the master jaw body portion 22,and the O-ring 76 providesa sliding seal between the two surfaces. The opposite, rear end of thesealing sleeve is disposed co-axially within the actuator 51, and anO-ring 78 situated within an internal groove 79 in the actuator providesa sliding seal between the actuator and the sleeve.

During normal operation of the chuck 13, axial movement of the actuator51 results in a corresponding radial displacement of the master jaw 21.In FIG. 7, the parts are shown with the master jaw in a radiallyoutward, workpiece releasing position with the actuator in its extremeleftward position. Axial movement of the drawbar to the right drives themaster jaw radially inward, to the point illustrated by the phantom line79.

The jaw body has a notch therein for receiving the sleeve flange 73,and,significantly,the O-ring 76 seals the jaw rear surface 77 for allpositions of the master jaw. Similarly, the rear end of the sleeveextends a sufficient distance into the actuator 51, so that over therange of axial movement of the actuator, the O-ring 78 maintains thedesired seal between the parts.

With the sleeve 70 in place, any particles or debris are trappedharmlessly within the sleeve and prevented from entering the jawpassages 23 or cam pin opening 35. If desired, a further O-ring seal 81may be provided around clamping plate legs 31 and 32 to seal thepassages 33a and 33b.

In another modification, the cam pin 36 has its outer and inner cammingportions 37 and 38, respectively, slightly offset around the pincircumference to compensate for the slight twist developed duringrotation of the pin. Were the camming portions not offset, the pin twistcould prevent the inner camming portion from reaching its fully clampedposition. FIG. 9 shows the inner camming portion 38 in clockwiserotation just as it begins to tightly cam clamping plate leg 32. FIG. 10shows the outer camming portion 36 for leg 31 at the same time, with itscamming surface offset counterclockwise a few degrees, for example by 5or so. When the cam pin is tightened, the camming portion 38 engages itsleg 32, and as twist develops in the pin, the lagging portion 37 rotatesinto its cammed position and cams its leg 31. As a result, the twocamming portions in their final clamped positions are identicallyoriented, and both legs are securely held and fully clamped to reducethe possibility of one leg working loose.

To further insure against accidental unlocking of the cam pin 36, alocking detent is provided to stop cam rotation in the unlockingdirection at an intermediate point while the serrated jaw surfaces 24and 24a are still partially locked. The cam pin has a head 85 thereonwith an annular groove 86 therearound, as shown in FIG. 6, and aspring-biased ball detent 87, held by spring 88, rides in the grooveduring cam rotation in the manner depicted in FIG. 11. The cam isillustrated in its fully locked position and is unlocked bycounterclockwise rotation in the direction of the arrow.

A first radial pocket 89 is inset into the pin head 86, and when the pin36 is rotated 180 from the position shown, the detent 87 snaps into thispocket and locks the pin in place. In this position the jaw serrations24 and 24a are completely disengaged, and the clamping jaws 21 may beadjusted by sliding along the clamping plate 29. A second, intermediatepocket 90 is also provided which engages the detent prior to completedisengagement of the jaw serrations. If during chuck operation, the pinshould work loose and begin to unlock, the detent would engage thepocket 90 to lock the pin at that point.

FIG. 6 shows in phantom outline, one of the clamping jaws 25 in aradially adjusted position. Because of the novel construction of theinvention, the clamping jaws can be readily moved and clamped in anydesired position, even further outward than that illustrated in thefigure. Similarly, the full workpiece engaging face of the jaw may bebored or machined away for a major portion of the jaw length, and thejaw can be continuously adjusted radially inward as long as some part ofthe jaw remains to be held by the clamping plate. In addition, the jawsare readily removed and replaced or, if desired, the same jaw can beturned and reinstalled on the chuck. In this latter fashion, either endof the jaw may be used to clamp a workpiece. Significantly, the jaw withall of its advantages is of simple, one-piece construction, and istherefore straightforward and inexpensive to manufacture.

It will be apparent from the foregoing that while particular forms ofthe invention have been illustrated and described, various modificationscan be made without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the invention be limitedexcept as by the appended claims.

I claim:

1. A chuck for clamping a workpiece in a machine comprising:

an annular body portion;

a plurality of radially extending passages in said body portion, saidpassages opening toward the front and being angularly spaced around thebody portion;

a master jaw in each of said passages and presenting a forward-facingsurface through the opening;

a clamping jaw for each master jaw and having a rear surface adapted tobe clamped against the forwardfacing surface on said master jaw;

a clamping plate for each clamping jaw, said clamping plates havingpairs of legs extending rearwardly therefrom into openings insaid masterjaws;

a radially extending passage in each master jaw into which said legsextend, said legs having openings therethrough aligned with saidlast-mentioned passages; and

a cam pin extending through each of said lastmentioned passages andthrough the pair of legs extending thereinto for moving the legs andclamping plates toward and away from the master jaws to clamp andrelease the clamping jaws on the master jaws.

2. The chuck defined in claim 1 in which:

said forward-facing and rear surfaces on said master and clamping jawshaving complementary serrations thereon spaced a common, substantiallysmall distance apart to interlock the clamping jaw on the master jaw andto provide for adjustment of the clamping jaw relative to the master jawin increments corresponding to the serration spacing when the clampingplate releases it from clamping engagement.

3. The chuck defined in claim 1 including:

biasing means between said master jaws and said body portion for biasingthe jaws toward workpiece releasing position; and

actuating means operated by the drawbar of the machine for moving thejaws against the bias into workpiece clamping position.

4. The chuck defined in claim 3 in which:

said actuating means comprises a member mounted to and movable with themachine drawbar; and

bell crank levers mounted in the chuck and having their opposite legsengaging respectively said actuating means and a master jaw, wherebyaxial movement of the drawbar and actuating means effects radialmovement of the jaws into and out of workpiece clamping position.

5. The chuck defined in claim 4 in which:

the chuck and the actuating means are separately threaded on the spindleof the machine and the drawbar thereof; and

10 means comprises:

locking pins slidable in the body portion and projectable into and outof openings in the master jaws; and

a crank pin engaging each locking pin for effective reciprocatingmovement thereof into and out of locking position.

8. The chuck defined in claim 1 in which:

said cam pin has cutout portions adjacent said leg openings whereby theremaining portions are eccentrically mounted with respect to the axis ofthe pin, said eccentric portions on turning of the pin, moving the legsand the clamping plate carried thereby to clamp and release the clampingjaw engagement with the master jaw.

9. The chuck as defined in claim 1 in which:

each clamping plate and the pair of legs thereon is received in aradially extending T-shaped slot in a clamping jaw so that the clampingjaw is radially slidably movable relative to said clamping plate whenreleased from the master jaw to provide for radial adjustment of theclamping jaw relative to the master jaw when released therefrom by theclamping plate.

10. The chuck defined in claim 1 in which:

each master jaw having a substantially cylindrical body portion receivedwithin a complementary radially extending, cylindrical passage in thechuck body portion and presenting said forward-facing surface throughsaid passage opening.

11. The chuck defined in claim 10 in which:

said master jaw body portion has a substantially cylindrical headthereon eccentrically mounted with respect to the body portion andreceived within a recess in the chuck body portion to prevent rotationof the master jaw in its passage.

12. The chuck defined in claim 11 including:

spring means in said chuck body portion bearing against the undersurface of said master jaw head to bias the master jaw toward workpiecereleasing position.

13. The chuck defined in claim 1 in which:

each clamping plate and the legs thereon are received in a radiallyextending slot in a clamping jaw, the clamping jaw in its releasedposition being radially movable relative to the clamping plate alongsaid slot to provide for radial adjustment of the clamping jaw relativeto the master jaw.

14. The chuck defined in claim 13 in which:

said radially extending slot extends for the length of said clamping jawso that said clamping jaw may be adjusted radially inwardly or outwardlythrough the point at which the clamping jaw is removed from the clampingplate.

15. The chuck defined in claim 14 in which:

said radially extending slot is T-shaped.

16. The chuck defined in claim 2 including:

biasing means for urging the clamping jaw away from the master jaw intoits released position, the clamping jaw being moved against the urgingof said biasing means into its clamped position on the master aw.

17. The chuck defined in claim 1 in which:

said annular body portion has an axially extending area and the radiallyextending passages in the body portion have openings communicating withsaid area; and

in which the chuck further includes means for sealing the last-mentionedopenings to prevent entry of contaminants therethrough into thepassages.

18. The chuck defined in claim 17 in which:

the sealing means includes a generally cylindrical sealing sleevedisposed axially within said body portion, whereby contaminants trappedtherein are prevented by the sleeve walls from radial movement into thebody passages.

19. The chuck defined in claim 18 in which:

the chuck further includes an actuator for moving the jaws radially intoworkpiece clamping position; and

the sealing sleeve having one axial portion telescoped with and insliding, sealed engagement with the axially movable actuator, the sleevehaving a further radially extending portion in sliding, sealedengagement with the radially movable master jaws, whereby the actuatorand master jaws are sealed to the sleeve over their range of operativepositions.

20. The chuck defined in claim 1 and including:

means for rotatably locking the cam pin to prevent accidental unlockingand release of the clamping aws.

21. The chuck defined in claim 20 in which:

the locking means includes a spring-biased detent adapted to engage andlock the pin at an intermediate point prior to complete release of theclamping aws.

22. The chuck defined in claim 8 wherein:

the eccentric camming portions of the cam pin are offset around the pincircumference with respect to one another to compensate for twist of thepin when turned, whereby the camming portions upon twist of the pin areoriented together to fully cam both legs. 23. A chuck for clamping aworkpiece in a machine comprising:

an annular body portion;

a plurality of radially extending substantially cylindrical passages insaid body, said passages opening toward the front of and being angularlyspaced around said annular body portion; and

a first jaw having a first substantially cylindrical body portionreceived within a corresponding one of said passages for radial movementwithin said passage, said jaw having a second body portion eccentricallymounted with respect to the first body portion and received within acorresponding recess in said annular body portion to prevent rotation ofsaid jaw in said passage.

24. The chuck defined in claim 23 in which:

the second body portion and its corresponding recess are substantiallycylindrical.

25. The chuck defined in claim 24 in which:

said second body portion has a greater diameter than said first bodyportion and forms a head thereon.

26. The chuck defined in claim 23 including:

a second jaw connected to said first jaw at the front of said bodyportion, said second jaw being a clamping jaw for engaging and clampinga workpiece; and

means for clamping both jaws into mating contact to interlock saidsecond jaw on said first jaw.

27. The chuck defined in claim 26 wherein:

said clamping means includes a clamping plate carrying the second jaw,the plate being actuable axially between clamped and released positionsbut restrained against radial movement, whereby the second jaw isradially adjustable along the clamping plate in the released position.

28. A chuck for clamping a workpiece in a machine comprising:

an annular body portion;

a radially extending passage in the body portion and opening along itslength toward the front of the body portion;

a master jaw in the passage for radial movement therealong;

a workpiece clamping jaw paired with the master jaw and having a rearsurface adapted to be releasably clamped against the forward facingsurface of the master jaw for radial movement of the jaw pair into andout of workpiece clamping position;

means for releasably clamping the workpiece clamping jaw to the masterjaw including a clamping member having at least one leg extendingtherefrom into the master jaw; and

means within the master jaw for moving the leg and clamping membertoward and away from the master jaw to clamp and release the clampingjaw on the master jaw.

29. The chuck defined in claim 28 in which:

the means for moving the leg and clamping includes a radially disposedcam pin within the master jaw having a cam portion for engaging andcamming the leg.

30. The chuck defined in claim 28 in which:

each clamping member and the leg thereon are received in a radiallyextending slot in the clamping jaw, the clamping jaw in its releasedposition being radially movable relative to the clamping plate alongsaid slot to provide for radial adjustment of the clamping jaw relativeto the master jaw.

31. The chuck defined in claim 30 in which:

said radially extending slot extends for the length of said clamping jawso that said clamping jaw may be adjusted radially inwardly or outwardlythrough the point at which the clamping jaw is removed from the clampingplate.

32. The chuck defined in claim 31 in which:

said radially extending slot is T-shaped.

33. The chuck defined in claim 28 in which:

said forward-facing and rear surfaces on said master and clamping jawshaving complementary serrations thereon spaced a common, substantiallysmall distance apart to interlock the clamping jaw on the master jaw andto provide for adjustment of the clamping jaw relative to the master jawin increments corresponding to the serration spacing when the clampingmember releases it from clamping engagement.

34. A workpiece clamping jaw for installation on a chuck, the chuckhaving a radially disposed master jaw to be paired with the clamping jawfor radially movethe jaw between its opposing ends and adapted toreceive a clamping plate, the plate being actuable to draw the saidforward and rear faces into clamped or released engagement, and releasedclamping jaw being adjustable radially along the plate.

1. A chuck for clamping a workpiece in a machine comprising: an annularbody portion; a plurality of radially extending passages in said bodyportion, said passages opening toward the front and being angularlyspaced around the body portion; a master jaw in each of said passagesand presenting a forwardfacing surface through the opening; a clampingjaw for each master jaw and having a rear surface adapted to be clampedagainst the forward-facing surface on said master jaw; a clamping platefor each clamping jaw, said clamping plates having pairs of legsextending rearwardly therefrom into openings in said master jaws; aradially extending passage in each master jaw into which said legsextend, said legs having openings therethrough aligned with saidlast-mentioned passages; and a cam pin extending through each of saidlast-mentioned passages and through the pair of legs extending thereintofor moving the legs and clamping plates toward and away from the masterjaws to clamp and release the clamping jaws on the master jaws.
 2. Thechuck defined in claim 1 in which: said forward-facing and rear surfaceson said master and clamping jaws having complementary serrations thereonspaced a common, substantially small distance apart to interlock theclamping jaw on the master jaw and to provide for adjustment of theclamping jaw relative to the master jaw in increments corresponding tothe serration spacing when the clamping plate releases it from clampingengagement.
 3. The chuck defined in claim 1 including: biasing meansbetween said masTer jaws and said body portion for biasing the jawstoward workpiece releasing position; and actuating means operated by thedrawbar of the machine for moving the jaws against the bias intoworkpiece clamping position.
 4. The chuck defined in claim 3 in which:said actuating means comprises a member mounted to and movable with themachine drawbar; and bell crank levers mounted in the chuck and havingtheir opposite legs engaging respectively said actuating means and amaster jaw, whereby axial movement of the drawbar and actuating meanseffects radial movement of the jaws into and out of workpiece clampingposition.
 5. The chuck defined in claim 4 in which: the chuck and theactuating means are separately threaded on the spindle of the machineand the drawbar thereof; and in which the actuating means and chuck areinterlocked to prevent relative movement therebetween.
 6. The chuckdefined in claim 1 including: means for locking the master jawsintermediate their extreme open and closed positions against radialmovement to facilitate a machining operation on the clamping jaws. 7.The chuck defined in claim 6 in which said locking means comprises:locking pins slidable in the body portion and projectable into and outof openings in the master jaws; and a crank pin engaging each lockingpin for effective reciprocating movement thereof into and out of lockingposition.
 8. The chuck defined in claim 1 in which: said cam pin hascutout portions adjacent said leg openings whereby the remainingportions are eccentrically mounted with respect to the axis of the pin,said eccentric portions on turning of the pin, moving the legs and theclamping plate carried thereby to clamp and release the clamping jawengagement with the master jaw.
 9. The chuck as defined in claim 1 inwhich: each clamping plate and the pair of legs thereon is received in aradially extending T-shaped slot in a clamping jaw so that the clampingjaw is radially slidably movable relative to said clamping plate whenreleased from the master jaw to provide for radial adjustment of theclamping jaw relative to the master jaw when released therefrom by theclamping plate.
 10. The chuck defined in claim 1 in which: each masterjaw having a substantially cylindrical body portion received within acomplementary radially extending, cylindrical passage in the chuck bodyportion and presenting said forward-facing surface through said passageopening.
 11. The chuck defined in claim 10 in which: said master jawbody portion has a substantially cylindrical head thereon eccentricallymounted with respect to the body portion and received within a recess inthe chuck body portion to prevent rotation of the master jaw in itspassage.
 12. The chuck defined in claim 11 including: spring means insaid chuck body portion bearing against the under surface of said masterjaw head to bias the master jaw toward workpiece releasing position. 13.The chuck defined in claim 1 in which: each clamping plate and the legsthereon are received in a radially extending slot in a clamping jaw, theclamping jaw in its released position being radially movable relative tothe clamping plate along said slot to provide for radial adjustment ofthe clamping jaw relative to the master jaw.
 14. The chuck defined inclaim 13 in which: said radially extending slot extends for the lengthof said clamping jaw so that said clamping jaw may be adjusted radiallyinwardly or outwardly through the point at which the clamping jaw isremoved from the clamping plate.
 15. The chuck defined in claim 14 inwhich: said radially extending slot is T-shaped.
 16. The chuck definedin claim 2 including: biasing means for urging the clamping jaw awayfrom the master jaw into its released position, the clamping jaw beingmoved against the urging of said biasing means into its clamped positionon the master jaw.
 17. The chuck defined in claim 1 in which: saidannular body portion has an axially extending area and the radiallyextending passages in the body portion have openings communicating withsaid area; and in which the chuck further includes means for sealing thelast-mentioned openings to prevent entry of contaminants therethroughinto the passages.
 18. The chuck defined in claim 17 in which: thesealing means includes a generally cylindrical sealing sleeve disposedaxially within said body portion, whereby contaminants trapped thereinare prevented by the sleeve walls from radial movement into the bodypassages.
 19. The chuck defined in claim 18 in which: the chuck furtherincludes an actuator for moving the jaws radially into workpiececlamping position; and the sealing sleeve having one axial portiontelescoped with and in sliding, sealed engagement with the axiallymovable actuator, the sleeve having a further radially extending portionin sliding, sealed engagement with the radially movable master jaws,whereby the actuator and master jaws are sealed to the sleeve over theirrange of operative positions.
 20. The chuck defined in claim 1 andincluding: means for rotatably locking the cam pin to prevent accidentalunlocking and release of the clamping jaws.
 21. The chuck defined inclaim 20 in which: the locking means includes a spring-biased detentadapted to engage and lock the pin at an intermediate point prior tocomplete release of the clamping jaws.
 22. The chuck defined in claim 8wherein: the eccentric camming portions of the cam pin are offset aroundthe pin circumference with respect to one another to compensate fortwist of the pin when turned, whereby the camming portions upon twist ofthe pin are oriented together to fully cam both legs.
 23. A chuck forclamping a workpiece in a machine comprising: an annular body portion; aplurality of radially extending substantially cylindrical passages insaid body, said passages opening toward the front of and being angularlyspaced around said annular body portion; and a first jaw having a firstsubstantially cylindrical body portion received within a correspondingone of said passages for radial movement within said passage, said jawhaving a second body portion eccentrically mounted with respect to thefirst body portion and received within a corresponding recess in saidannular body portion to prevent rotation of said jaw in said passage.24. The chuck defined in claim 23 in which: the second body portion andits corresponding recess are substantially cylindrical.
 25. The chuckdefined in claim 24 in which: said second body portion has a greaterdiameter than said first body portion and forms a head thereon.
 26. Thechuck defined in claim 23 including: a second jaw connected to saidfirst jaw at the front of said body portion, said second jaw being aclamping jaw for engaging and clamping a workpiece; and means forclamping both jaws into mating contact to interlock said second jaw onsaid first jaw.
 27. The chuck defined in claim 26 wherein: said clampingmeans includes a clamping plate carrying the second jaw, the plate beingactuable axially between clamped and released positions but restrainedagainst radial movement, whereby the second jaw is radially adjustablealong the clamping plate in the released position.
 28. A chuck forclamping a workpiece in a machine comprising: an annular body portion; aradially extending passage in the body portion and opening along itslength toward the front of the body portion; a master jaw in the passagefor radial movement therealong; a workpiece clamping jaw paired with themaster jaw and having a rear surface adapted to be releasably clampedagainst the forward facing surface of the master jaw for radial movementof the jaw pair into and out of workpiece clamping position; means forreleasably clamping the workpiece clamping jaw to the master jawincluding a clAmping member having at least one leg extending therefrominto the master jaw; and means within the master jaw for moving the legand clamping member toward and away from the master jaw to clamp andrelease the clamping jaw on the master jaw.
 29. The chuck defined inclaim 28 in which: the means for moving the leg and clamping includes aradially disposed cam pin within the master jaw having a cam portion forengaging and camming the leg.
 30. The chuck defined in claim 28 inwhich: each clamping member and the leg thereon are received in aradially extending slot in the clamping jaw, the clamping jaw in itsreleased position being radially movable relative to the clamping platealong said slot to provide for radial adjustment of the clamping jawrelative to the master jaw.
 31. The chuck defined in claim 30 in which:said radially extending slot extends for the length of said clamping jawso that said clamping jaw may be adjusted radially inwardly or outwardlythrough the point at which the clamping jaw is removed from the clampingplate.
 32. The chuck defined in claim 31 in which: said radiallyextending slot is T-shaped.
 33. The chuck defined in claim 28 in which:said forward-facing and rear surfaces on said master and clamping jawshaving complementary serrations thereon spaced a common, substantiallysmall distance apart to interlock the clamping jaw on the master jaw andto provide for adjustment of the clamping jaw relative to the master jawin increments corresponding to the serration spacing when the clampingmember releases it from clamping engagement.
 34. A workpiece clampingjaw for installation on a chuck, the chuck having a radially disposedmaster jaw to be paired with the clamping jaw for radially movementtogether into and out of workpiece clamping positions, the clamping jawcomprising: a one-piece solid structure having opposing ends; arearwardly facing surface between said ends to be paired with a forwardfacing surface of the master jaw; a radially extending, T-shaped slotextending through the jaw between its opposing ends and adapted toreceive a clamping plate, the plate being actuable to draw the saidforward and rear faces into clamped or released engagement, and releasedclamping jaw being adjustable radially along the plate.